CN109146800B - Cone beam computed tomography method for correcting image and system - Google Patents
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- G06T5/80—
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/10—Image acquisition modality
- G06T2207/10072—Tomographic images
- G06T2207/10081—Computed x-ray tomography [CT]
Abstract
This application involves a kind of cone beam computed tomography method for correcting image and systems.The described method includes: obtaining background projection image and correction model body projected image in the first condition, multipotency curve is obtained according to background projection image and correction model body projected image, according to multipotency curve acquisition list energy curve, according to multipotency curve and single energy curve, corrects acquired projected image to be corrected under second condition and generate target cone beam computed tomography image.The higher multipotency curve of accuracy and single energy curve can be obtained by second condition using this method, the projected image to be corrected of measuring targets is accurately corrected, and the accuracy of hardening correcting is improved.
Description
Technical field
This application involves Computed tomography fields, more particularly to a kind of cone beam computed tomography image
Bearing calibration and cone beam computed tomography image correction system.
Background technique
Cone beam computed tomography (Cone Beam Computed Tomography) due to it is fast with scanning speed,
Radiate utilization rate height and it is at low cost the advantages that, be widely used in medical diagnosis and therapy field.Since the multipotency of ray can be led
It causes to contain artifact phenomenon in cone beam computed tomography image, this artifact phenomenon is known as beam hardening effect, influences cone-beam
The quality of computer tomography image.
In order to correct artifact phenomenon, can be put it into the prior art using the uniform die body of cylinder as correction model body
Within the scope of imaging region, so that in the cone beam computed tomography image reconstructed, the outer profile comprising entire cylinder is utilized
The scan geometry parameter and forward projection algorithm of cone beam computed tomography system can simulation calculation go out different rays and wear
Cross cylinder die body length value and find it is right in the cylindrical wire integration data scanned in cone beam computed tomography system
The line integral value answered fits multipotency curve and single energy curve by length value and corresponding line integral value；To other objects into
When row scanning, so that it may multipotency line integral value be transformed to single energy line product using the corresponding relationship of multipotency curve and single energy curve
Score value completes hardening correcting, and the data after recycling correction carry out cone beam computed tomography image reconstruction, obtains no hardening
The CT image of artifact.
Under actual conditions, the possible volume of the object of scanning can be bigger, and the length that ray passes through object can be longer, still, existing
The length for having the ray in technology to pass through die body is also limited, and length and corresponding line can only be fitted within the scope of certain length
The relation curve of integrated value, the multipotency curve being fitted in the prior art can only be good to the calibration result within the scope of certain length, surpass
It may be inaccurate for crossing the curve matching of certain length range, in this way, being more than the multipotency line integral value school of certain length range
Just arriving single energy line integrated value error can be bigger, influences final hardening correcting effect.Therefore, prior art hardening correcting exists quasi-
The low problem of true property.
Summary of the invention
Based on this, it is necessary to there is a problem of that accuracy is low for above-mentioned hardening correcting, it is disconnected to provide a kind of cone-beam computer
Layer image bearing calibration and system.
A kind of cone beam computed tomography method for correcting image, comprising the following steps:
Obtain background projection image, wherein background projection image is that detector carries out gas medium in the first condition
The angularly image that circumference exposure scan is detected, plane where first condition is detector are parallel to angularly circumference exposure
What the Pivot axle of scanning, the central ray of radiographic source passed perpendicularly through Pivot axle and detector is parallel to Pivot axle
The midpoint on side boundary irradiated by the central ray；
Obtain correction model body projected image, wherein correction model body projected image is detector in the first condition to correction
Die body carries out image that angularly circumference exposure scan is detected, and Correction Die is to be placed in imaging visible area and section
Diameter is less than the die body of the diameter of imaging visible area, and imaging visible area is field angle under first condition at Pivot axle
Imageable areas；
Multipotency curve is obtained according to background projection image and correction model body projected image, it can be bent according to multipotency curve acquisition list
Line, wherein multipotency curve is used to indicate the relationship of multipotency line integral value and length value, and single energy curve is for indicating that list can line integral
The relationship of value and length value；
According to multipotency curve and single energy curve, corrects projected image to be corrected and generate target cone beam computed tomography
Image, wherein projected image to be corrected is that detector measuring targets carry out angularly circumference exposure scan under a second condition
The image detected, second condition are that plane is parallel to Pivot axle, central ray passes perpendicularly through rotation at detector place
Central axis and central ray vertical irradiation is at the center of detector, object under test is to be placed on the object of Pivot axle and be in
In the environment of gas medium.
In one embodiment, cone beam computed tomography method for correcting image, further comprising the steps of:
According toThe diameter of imaging visible area is obtained,
Wherein, D be imaged visible area diameter, L be detector detectable area length, SAD be radiographic source with
The distance of Pivot axle, SDD are the vertical range of radiographic source and detector.
In one embodiment, multipotency curve is obtained according to background projection image and correction model body projected image, according to more
The step of energy curve acquisition list energy curve, comprising the following steps:
The background projection image of correction model body projected image and corresponding angle is subjected to logarithmic transformation, and obtains compensation line product
Partial image；
Initial cone beam computed tomography image is established according to compensation line integral image, in initial cone-beam computer tomography
Image is partitioned into the region of correction model body, and generates and divide domain cone beam computed tomography image, wherein divides domain cone-beam meter
The pixel value in the region of correction model body is preset non-zero value in calculation machine tomographic imaging image, divides domain cone beam computed tomography figure
Pixel value as in other than the region of correction model body is zero；
According to domain cone beam computed tomography image is divided, the corresponding length value of each detection member of detector and length are obtained
It is worth corresponding line integral value；
It is fitted according to length value and the corresponding line integral value of length value and obtains multipotency curve；
According to multipotency curve acquisition list energy curve, wherein single energy curve is multipotency curve in the tangent line that length value is at zero.
In one embodiment, the background projection image of correction model body projected image and corresponding angle is subjected to logarithm change
It changes, and the step of obtaining compensation line integral image, comprising the following steps:
According toObtain compensation line integral image, wherein ln is pair that the truth of a matter is e
Number operation, integral are compensation line integral image, and P_cylinder is correction model body projected image, and P_air is corresponding angle
Background projection image, s is the serial number of angularly angle in circumference exposure scan, and integral (s) is the correction of s-th of angle
Line integral image, P_cylinder (s) are the correction model body projected image of s-th of angle, and P_air (s) is the back of s-th of angle
Scape projected image,For the background projection image of s-th angle and the respective pixel of correction model body projected image
Pixel value ratio.
In one embodiment, according to domain cone beam computed tomography image is divided, it is right to obtain each detection member of detector
The step of length value and length value answered corresponding line integral value, comprising the following steps:
According in the length of the detectable area of detector, the width of the detectable area of detector, radiographic source and rotation
Distance, the vertical range of radiographic source and detector of mandrel, detection member of the calculating detector under default rotation angle are corresponding
Length value, wherein the corresponding length value of detection member is the ray of radiographic source when the ray of radiographic source reaches the detection member of detector
Penetrate the length of correction model body；
The line integral value for detecting first corresponding position is searched in the corresponding compensation line integral image of default rotation angle.
In one embodiment, it according to multipotency curve and single energy curve, corrects projected image to be corrected and generates target cone
The step of beam computerized tomographic imaging image, comprising the following steps:
Obtain projected image to be corrected；
According to projected image to be corrected, multipotency curve and single energy curve, corrects projected image to be corrected and obtain to be corrected
Single energy line integrated value of projected image；
Target cone beam computed tomography image is generated according to single energy line integrated value of projected image to be corrected.
In one embodiment, according to projected image to be corrected, multipotency curve and single energy curve, perspective view to be corrected is corrected
As and the step of obtain single energy line integrated value of projected image to be corrected, comprising the following steps:
The background projection image of projected image to be corrected and corresponding angle is subjected to logarithmic transformation, and obtains line product to be corrected
Partial image；
The corresponding length value to be corrected of multipotency line integral value of line integral image to be corrected is searched in multipotency curve,
In, the multipotency line integral value of projected image to be corrected is the pixel value of pixel in projected image to be corrected；
Using length value to be corrected in the corresponding single energy line integrated value of single energy curve as single energy line of projected image to be corrected
Integrated value.
In one embodiment, the array size of the detection member of detector is M × N, and background projection image, correction model body are thrown
The matrix size of shadow image and projected image to be corrected is M × N, wherein M and N is positive integer.
A kind of cone beam computed tomography image correction system, system include:
Background projection image obtains module, for obtaining background projection image, wherein background projection image is at first
Detector carries out the image that angularly circumference exposure scan is detected to gas medium under part, and first condition is detector place
Plane be parallel to the angularly Pivot axle of circumference exposure scan, the central ray of radiographic source pass perpendicularly through Pivot axle and
The midpoint on the side boundary for being parallel to Pivot axle of detector is irradiated by the central ray；
Correction model body projected image obtains module, for obtaining correction model body projected image, wherein correction model body perspective view
As carrying out the image that angularly circumference exposure scan is detected, Correction Die to correction model body for detector in the first condition
To be placed in imaging visible area and diameter of section is less than the die body of the diameter of imaging visible area, imaging visible area is the
Imageable areas of the field angle at Pivot axle under the conditions of one；
Single energy curve acquisition module, for obtaining multipotency curve according to background projection image and correction model body projected image,
According to multipotency curve acquisition list energy curve, wherein multipotency curve is used to indicate the relationship of multipotency line integral value and length value, Dan Neng
Curve is used to indicate the relationship of single energy line integrated value and length value；
Projection image correction module to be corrected, for correcting projected image to be corrected according to multipotency curve and single energy curve
And generate target cone beam computed tomography image, wherein projected image to be corrected is that detector is treated under a second condition
It surveys object and carries out the image that angularly circumference exposure scan is detected, plane where second condition is detector is parallel to rotation
Central axis, central ray pass perpendicularly through Pivot axle and central ray vertical irradiation at the center of detector, and object under test is
It is placed on the object of Pivot axle and is in the environment of gas medium.
A kind of computer equipment can be run on a memory and on a processor including memory, processor and storage
The step of computer program, processor realizes cone beam computed tomography method for correcting image when executing computer program.
A kind of computer readable storage medium is stored thereon with computer program, when computer program is executed by processor
The step of realizing cone beam computed tomography method for correcting image.
Above-mentioned cone beam computed tomography method for correcting image, system, computer equipment and storage medium, pass through second
Condition obtains the higher multipotency curve of accuracy and single energy curve, and the projected image to be corrected of measuring targets carries out accurate school
Just, the accuracy of hardening correcting is improved.
Detailed description of the invention
Fig. 1 (a) is the structural schematic diagram of the cone beam computed tomography system of first condition in one embodiment；
Fig. 1 (b) is the structural schematic diagram of the cone beam computed tomography system of second condition in one embodiment；
Fig. 2 is the flow chart of cone beam computed tomography method for correcting image in one embodiment；
Fig. 3 is the flow chart of cone beam computed tomography method for correcting image in another embodiment；
Fig. 4 is the schematic diagram of multipotency curve and single energy curve in another embodiment；
Fig. 5 is the schematic diagram of the multipotency curve and single energy curve under conventional method；
Fig. 6 is the structural schematic diagram of cone beam computed tomography image correction system in one embodiment；
Fig. 7 is the internal structure chart of computer equipment in one embodiment.
Specific embodiment
It is with reference to the accompanying drawings and embodiments, right in order to which the objects, technical solutions and advantages of the application are more clearly understood
The application is further elaborated.It should be appreciated that specific embodiment described herein is only used to explain the application, not
For limiting the application.
Cone beam computed tomography method for correcting image provided by the present application can be applied to bore as shown in Fig. 1 (a)
In beam computerized computed tomography (SPECT) system.Wherein, detector 10 is located on the direction of illumination of the central ray 22 of radiographic source 21, detection
Device 10 can be used for detecting and generating image, and the length of 10 detectable area of detector is L, and detector 10 hangs down with radiographic source 21
Straight distance is SDD, and Pivot axle O is located on SDD, and Pivot axle O is SAD, cone-beam computer at a distance from radiographic source 21
Computed tomography (SPECT) system forms imaging visible area 30 at Pivot axle O, and imaging visible area 30 can be used for placing correction
Die body or object under test, the diameter of imaging visible area 30 are D.The specific location of detector shown in Fig. 1 (a) is only intended to lift
Example explanation, is not especially limited.
In one embodiment, as shown in Fig. 2, Fig. 2 is cone beam computed tomography image rectification in one embodiment
The flow chart of method provides a kind of cone beam computed tomography method for correcting image in the present embodiment, applies in this way
It is illustrated for cone beam computed tomography system in Fig. 1 (a), comprising the following steps:
Step S210: background projection image is obtained, wherein background projection image is detector in the first condition to gas
Medium carries out the image that angularly circumference exposure scan is detected, and plane where first condition is detector is parallel to angularly
What the Pivot axle of circumference exposure scan, the central ray of radiographic source passed perpendicularly through Pivot axle and detector is parallel to rotation
The midpoint for turning the side boundary of central axis is irradiated by central ray.
Radiographic source be divergent-ray, radiographic source can be a transmitting focus in a wavelength range, radiographic source is sent out
The ray shot out can form the light beam of taper, and the central symmetry axis of the light beam of taper can represent radiographic source radiation direction
Place straight line, can be used as the central ray of radiographic source by the ray at central symmetry axis.It is exposed carrying out angularly circumference
Central ray can be with detector described in vertical irradiation when optical scanning, and radiographic source and detector are respectively using Pivot axle as rotary shaft
It is rotated.
In this step, if be described from the angle for overlooking Pivot axle, if detector is along rotation center
It is rotated counterclockwise centered on axis, it is possible to understand that detector is rotated to the left.For example, first condition can be detection
Device is placed under the central ray of radiographic source the central ray vertical irradiation of the left side of direction of illumination and radiographic source in detector
The midpoint of right side edge；Alternatively, first condition may be that detector is placed on direction of illumination under the central ray of radiographic source
The central ray vertical irradiation of right side and radiographic source is at the left side edge midpoint of detector.Detector is with one of modes of emplacement
It is placed on shown in situation such as Fig. 1 (a) in cone beam computed tomography system, Fig. 1 (a) is first condition in one embodiment
Cone beam computed tomography system structural schematic diagram, at this point, with detector citing, it will be understood that the detector is
The central ray vertical irradiation of the left side of direction of illumination and radiographic source is placed under the central ray of radiographic source on the right side of detector
The midpoint of side edge.The specific location of detector shown in Fig. 1 (a) is only intended to for example, being not especially limited.
Gas medium can be the required atmosphere under imaging circumstances, for example, it may be air, rare gas,
Nitrogen, a certain proportion of mixed gas, ionic steam, certain pressure intensity or temperature gas.Needs are such as imaged in vacuum environment, gas
The state of body medium also could alternatively be the state of no gas medium, to form vacuum environment.Angularly circumference exposure scan can
To detect the image under multiple angles.Described parallel and vertical state allows to deposit angular deviation in the reasonable scope.
Step S220: correction model body projected image is obtained, wherein correction model body projected image is to detect in the first condition
Device carries out the image that angularly circumference exposure scan is detected to correction model body, and Correction Die is to be placed on imaging visible area
Interior and diameter of section is less than the die body of the diameter of imaging visible area, and imaging visible area is that field angle is rotating under first condition
The imageable areas of central axis.
In this step, correction model body in imaging visible area, can make as far as possible cylindrical center's line of correction model body with
Rotation centerline substantially overlaps, and detects available correction model body projected image by carrying out to correction model body.
Correction model body can be the shapes such as cylinder, rectangle；The composition material of correction model body can be homogeneous substance, i.e.,
The density of correction model body is uniform, for example equivalent water or pmma material can be selected as etc..
Step S230: multipotency curve is obtained according to background projection image and correction model body projected image, according to multipotency curve
The single energy curve of acquisition, wherein multipotency curve is used to indicate the relationship of multipotency line integral value and length value, and single energy curve is for indicating
The relationship of single energy line integrated value and length value.
In this step, sweeping for radiographic source and detector can be simulated according to background projection image and correction model body projected image
It retouches imaging process and fits multipotency curve, further according to multipotency curve acquisition list energy curve.
Step S240: it according to multipotency curve and single energy curve, corrects projected image to be corrected and generates the calculating of target cone-beam
Machine tomographic imaging image, wherein projected image to be corrected is that detector measuring targets are angularly justified under a second condition
The image that all exposure scans are detected, plane where second condition is detector is parallel to Pivot axle, central ray hangs down
Direct puncture crosses Pivot axle and central ray vertical irradiation at the center of detector, and object under test is to be placed on Pivot axle
Object and in gas medium environment in.
Projected image acquisition process to be corrected radiographic source central ray vertical irradiation at the center of detector, detection
Device can be imaged in the center of field angle, and as shown in the position of detector in Fig. 1 (b), Fig. 1 (b) is in one embodiment
The structural schematic diagram of the cone beam computed tomography system of second condition.
It, can be according to the projected image to be corrected of the multipotency curve being fitted and single energy curve measuring targets in this step
It is corrected, obtains target cone beam computed tomography image.
It is bent to obtain the higher multipotency of accuracy by second condition for above-mentioned cone beam computed tomography method for correcting image
Line and single energy curve, the projected image to be corrected of measuring targets are accurately corrected, and the accuracy of hardening correcting is improved.
Under the prior art, multipotency curve is obtained generally by the cone beam computed tomography system under second condition
With it is single can curve, i.e., multipotency curve under the prior art and it is single can curve be multipotency curve under a second condition and it is single can be bent
Line.And in the present embodiment, by step S210, step S220 and step S230, obtain multipotency curve in the first condition
With single energy curve.
In the present embodiment, compared to second condition, the field angle under first condition is greater than under second condition first condition
Field angle, in Fig. 1 (a) under first condition corresponding imaging visible area 30 be greater than in Fig. 1 (b) under second condition it is corresponding at
As visible area 30 '.Since imaging corresponding under first condition visible area 30 is larger, pass through background projection image and straightening die
During body projected image simulates the scanning imagery of radiographic source and detector, simulate acquired length value and line integral value it
Between corresponding relationship quantity is more and the range of length value is longer, the range of length value is longer.The acquired length value of simulation
Range is longer, and credible and true scope is bigger in the multipotency curve of fitting, so that it may improve the accuracy of multipotency curve.Cause
This, obtains the higher multipotency curve of accuracy and single energy curve by second condition, the standard of hardening correcting successively can be improved
True property.
Detector in the present embodiment can be planar detector, be also possible to the detector with cylindrical shape.Work as tool
Cylinder where having the detector of cylindrical shape can be parallel to Pivot axle, and the straight edge line of cylinder is parallel in rotation at this time
Mandrel.Detector in the present embodiment can also be with the matched spherical surface detector of radiographic source, be unable to satisfy spherical surface at this time
It is parallel to Pivot axle, can be vertical with Pivot axle by the normal direction of spherical surface or intersect and can meet correspondence image
Detection.
In one embodiment, cone beam computed tomography method for correcting image, further comprising the steps of:
According toThe diameter of imaging visible area is obtained,
Wherein, as shown in Fig. 1 (a), D is the diameter that visible area is imaged, and L is the length of the detectable area of detector,
SAD is radiographic source at a distance from Pivot axle, and SDD is the vertical range of radiographic source and detector.
Above-mentioned cone beam computed tomography method for correcting image, the angle of field angle is larger in the first condition, this is right
The diameter for the imaging visible area answered is also larger, which can satisfy the correction model body of larger size；And
Under the correction model body of larger size, the length value simulated can achieve longer range, expand credible and quasi- in multipotency curve
True range improves the accuracy of multipotency curve.
In one embodiment, multipotency curve is obtained according to background projection image and correction model body projected image, according to more
The step of energy curve acquisition list energy curve, comprising the following steps:
Step S231: the background projection image of correction model body projected image and corresponding angle is subjected to logarithmic transformation, and is obtained
Take compensation line integral image.
It may include exposure scan under different angle in correction model body projected image and background projection image respectively to be detected
Image.The correction model body projected image and background projection image of equal angular are subjected to logarithmic transformation, obtain the equal angular
Under compensation line integral image, the similarly compensation line integral image of available all angles.
Step S232: initial cone beam computed tomography image is established according to compensation line integral image, in initial cone-beam
Computer tomography image segmentation goes out the region of correction model body, and generates and divide domain cone beam computed tomography image, wherein
The pixel value for dividing the region of correction model body in domain cone beam computed tomography image is preset non-zero value, divides domain cone-beam computer
Pixel value in tomographic imaging image other than the region of correction model body is zero.
In this step, initial cone beam computed tomography image is rebuild using compensation line integral image, forms three-dimensional square
Battle array, the region of correction model body is partitioned into using image Segmentation Technology, the pixel value in region is set as preset non-zero value, is preset non-
Zero is the numerical value being not zero, such as preset non-zero value can be 1, and the pixel value outside region is set as 0, and what is generated at this time is point
Domain cone beam computed tomography image.
Step S233: according to domain cone beam computed tomography image is divided, the corresponding length of each detection member of detector is obtained
Angle value and the corresponding line integral value of length value.
In this step, it can simulate and the central ray for calculating radiographic source passes through the length of correction model body, and find out this
The corresponding line integral value of length.For example, being to rotate the case where angle is 90 ° in point domain cone beam computed tomography image
Example calculates separately center of the radiographic source respectively with radiographic source in the line of each detection member of detector using forward projection algorithm and penetrates
Line passes through the length value of correction model body, while finding rotation angle is to correspond to each spy in 90 ° of corresponding compensation line integral images
Survey the line integral value under first position.
Step S234: it is fitted according to length value and the corresponding line integral value of length value and obtains multipotency curve.
Multiple fitting of a polynomial is carried out using length value and line integral value, obtains multipotency curve.
Step S235: according to multipotency curve acquisition list energy curve, wherein it is single can curve be multipotency curve in length value be zero
The tangent line at place.
Multipotency curve near tangent is made by coordinate origin, which is single energy curve.
Above-mentioned cone beam computed tomography method for correcting image, by rebuilding initial cone beam computed tomography figure
Picture, is simulated and the central ray for calculating radiographic source passes through the length of correction model body, and finds out the corresponding line integral value of the length,
In order to be fitted multipotency curve and generate single energy curve.
In one embodiment, the background projection image of correction model body projected image and corresponding angle is subjected to logarithm change
It changes, and the step of obtaining compensation line integral image, comprising the following steps:
According toObtain compensation line integral image, wherein ln is pair that the truth of a matter is e
Number operation, integral are compensation line integral image, and P_cylinder is correction model body projected image, and P_air is background plane
Image, s are the serial number of angle in angularly circumference exposure scan, and integral (s) is the compensation line integrogram of s-th of angle
Picture, P_cylinder (s) are the correction model body projected image of s-th of angle, and P_air (s) is the background plane figure of s-th of angle
Picture,For the pixel value of the respective pixel of the background projection image and correction model body projected image of s-th angle
Ratio.
Above-mentioned cone beam computed tomography method for correcting image, to correction model body projected image and background projection image into
After row processing, the compensation line integral image of available corresponding position.
In one embodiment, according to domain cone beam computed tomography image is divided, it is right to obtain each detection member of detector
The step of length value and length value answered corresponding line integral value, comprising the following steps:
Step S236: according to the length of the detectable area of detector, the width of the detectable area of detector, radiographic source
With at a distance from Pivot axle, the vertical range of radiographic source and detector, detection of the calculating detector under default rotation angle
The corresponding length value of member, wherein the corresponding length value of detection member is ray when the ray of radiographic source reaches the detection member of detector
The ray in source penetrates the length of correction model body.
Since central ray penetrates correction model body when length value reaches the detection member of detector for the central ray of radiographic source
Length corresponding length value can be calculated according to the positional relationship of radiographic source, detector and correction model body.
Step S236: the line product for detecting first corresponding position is searched in the corresponding compensation line integral image of default rotation angle
Score value.
Each position of compensation line integral image corresponds to corresponding detection member.
Above-mentioned cone beam computed tomography method for correcting image, can accurately and efficiently obtain length value and line integral
The relationship of value improves the accuracy of subsequent acquired multipotency curve and single energy curve.
In one embodiment, it according to multipotency curve and single energy curve, corrects projected image to be corrected and generates target cone
The step of beam computerized tomographic imaging image, comprising the following steps:
Step S241: projected image to be corrected is obtained.
Step S242: it according to projected image to be corrected, multipotency curve and single energy curve, corrects projected image to be corrected and obtains
Take single energy line integrated value of projected image to be corrected.
Step S243: target cone beam computed tomography figure is generated according to single energy line integrated value of projected image to be corrected
Picture.
Above-mentioned cone beam computed tomography method for correcting image, by projected image to be corrected according to multipotency curve acquisition pair
The single energy line integrated value answered generates target cone beam computed tomography image according to single energy line integrated value, completes cone-beam and calculates
The accuracy of the correction of machine tomographic imaging image, target cone beam computed tomography image is high.
In one embodiment, according to projected image to be corrected, multipotency curve and single energy curve, perspective view to be corrected is corrected
As and the step of obtain single energy line integrated value of projected image to be corrected, comprising the following steps:
Step S244: the background projection image of projected image to be corrected and corresponding angle is subjected to logarithmic transformation, and is obtained
Line integral image to be corrected.
The background projection image of projected image to be corrected and corresponding angle is subjected to logarithmic transformation, removes background or noise
It influences, optimizes line integral image to be corrected, in order to obtain the line integral image to be corrected containing object under test.
Step S245: the corresponding length to be corrected of multipotency line integral value of line integral image to be corrected is searched in multipotency curve
Angle value, wherein the multipotency line integral value of projected image to be corrected is the pixel value of pixel in projected image to be corrected.
Step S245: using length value to be corrected in the corresponding single energy line integrated value of single energy curve as projected image to be corrected
Single energy line integrated value.
Above-mentioned cone beam computed tomography method for correcting image accurately obtains single energy line product of projected image to be corrected
Score value, can accurately show object under test, and the accuracy of single energy line integrated value is high.
In one embodiment, the array size of the detection member of detector is M × N, and background projection image, correction model body are thrown
The matrix size of shadow image and projected image to be corrected is M × N, wherein M and N is positive integer.
Above-mentioned cone beam computed tomography method for correcting image, acquired background projection image, correction model body projection
The matrix size of image and projected image to be corrected is related with the array size of detection member of detector, and the array for detecting member is got over
Greatly, the quantity of the relationship of the length value of acquisition and line integral value is more, and the accuracy of the multipotency curve of fitting can be improved.
The matrix size of image can be used for reflecting the quantity of pixel in image, the more big then image of the matrix size of image
Pixel quantity it is more.The matrix size of image is related with the array size of detection member of detector, such as when detector
When detection member is corresponded with the pixel in image, then the array size phase of the detection member of the matrix size of image and detector
Together, such as be also possible to detector several detection members and corresponded to each other with the pixel in image, then the matrix size and spy of image
There are positively related relationships for the array size of the detection member of survey device.
In another embodiment, as shown in figure 3, Fig. 3 is cone beam computed tomography image in another embodiment
The flow chart of bearing calibration provides a kind of cone beam computed tomography method for correcting image in the present embodiment, answers in this way
For being illustrated for the cone beam computed tomography system in Fig. 1 (a), comprising the following steps:
(1) scan parameter values in cone beam computed tomography system are obtained, comprising: 21 focus of radiographic source to system is revolved
The distance for turning central axis O is SAD, and SAD=23cm, the distance of 21 focus of radiographic source to 10 plane of detector is SDD, SDD=
63cm, the length of detector 10 are L, L=13cm, 10 width W=13cm of detector, and the detection element array on detector 10 is
1024 × 1024 matrix, shown in the top view of cone beam computed tomography system such as Fig. 1 (a).The initial cone-beam meter rebuild
Calculation machine tomographic imaging image divides in domain cone beam computed tomography image and target cone beam computed tomography image respectively
Including 400 CT (computer tomography) images, and the image array size of each CT is 512 × 512, detector detection
First size is 0.127mm × 0.127mm, and reconstruction divides domain cone beam computed tomography image and target cone-beam computer tomography
The voxel size of image is respectively 0.2mm*0.2mm*0.2mm.
(2) detector is to left 6.5cm, as shown in the position of detector in Fig. 1 (a), and fictionalizes on the right side of detector
Next to an equal amount of dummy detector 10 ', the length of the size of the entire detector including dummy detector at this time
It is 13cm for 26cm and width.
(3) parameter of the entire detector after utilizing the size in (1) in parameter and (2) to increase, it is visual to calculate imaging
The diameter in region 30, the diameter of imaging visible area 30 are D, D=16cm, calculation formula are as follows:
(4) the cylinder die body that a diameter is 15cm is made, the die body material of the cylinder die body is uniform organic glass；
(5) in cone beam computed tomography system, it is not put into any imaging object, carries out angularly 360 degree of exposures
Scanning (detector and radiographic source along Pivot axle is synchronous rotate a circle counterclockwise) obtains 400 air projected images, air
The collection of projected image is combined into P_air, and the image array size of every air projected image is 1024 × 1024；
(6) cylinder die body is put into the imaging visible area 30 in cone beam computed tomography system, so that cylinder
The center line and Pivot axle of die body substantially overlap, and carrying out angularly 360 degree of exposure scans, (detector and radiographic source are along rotation
Central axis synchronizes to rotate a circle counterclockwise) 400 cylinder die body projected images are obtained, cylinder die body projection image collection is P_
Cylinder, the image array size of every cylinder die body projected image are 1024 × 1024；
(7) the air projected image under each Zhang Yuanzhu die body projected image and corresponding angle is done into logarithmic transformation, obtained
Compensation line integral image, the collection of compensation line integral image are combined into integral, and calculation formula is
Wherein, ln is the logarithm operation that the truth of a matter is e, and integral is compensation line integral image, and P_cylinder is cylinder
Phantom projection image, P_air are air projected image, serial number of the s for angle in angularly circumference exposure scan, integral
It (s) is the compensation line integral image of s-th of angle, P_cylinder (s) is the cylinder die body projected image of s-th of angle, P_
Air (s) is the air projected image of s-th of angle,For the air projected image and cylinder of s-th of angle
The ratio of the pixel value of the respective pixel of phantom projection image.；
(8) it is rebuild using compensation line integral image, obtains the CT image that 400 matrix sizes are 512 × 512, group
At cone beam computed tomography image, three-dimensional matrice size is 512 × 512 × 400, and utilizes the threshold in image Segmentation Technology
Value partitioning algorithm is partitioned into the cylindrical region of cone beam computed tomography image, and the pixel value in cylindrical region is set as 1, area
Overseas pixel value is set as 0；
(9) the entire parameter detector after utilizing the size in (1) in parameter and (2) to increase, to three-dimensional matrice in (8) into
Row Computer Simulation emulates the scanning process of radiographic source and detector in cone beam computed tomography system, using preceding to throwing
The line (simulation X-ray) that shadow algorithm calculates radiographic source when rotation angle is 90 ° to different detection members passes through and divides domain cone-beam meter
The length of calculation machine tomographic imaging Circle in Digital Images column die body, while finding when rotation angle is 90 ° and corresponding in compensation line integral image
The same line integral value detected under first position, the corresponding compensation line integral image are the 90/th (360/400)=100 corrections
Line integral image, i.e. integral (100) traverse the detection member on all detectors, thus have found 1024 altogether ×
1024 length values and 1024 × 1024 line integral values and their corresponding relationship；
(10) 6 order polynomial fittings are carried out using length Value Data and line integral Value Data, obtains multipotency curve, then pass through
Coordinate origin seeks tangent line to the multipotency curve, which is ideal single energy curve, to establish multipotency curve and list
Can curve corresponding relationship, multipotency curve and it is single can the abscissa of curve indicate the length across cylinder die body, ordinate is pair
The line integral value answered, as shown in figure 4, Fig. 4 is the schematic diagram of multipotency curve and single energy curve in another embodiment, solid dot is
The sampled point of the length value and line integral value that obtain is emulated, solid-line curve is the multipotency curve of fitting, and number line is the list after fitting
It can curve；
(11) detector is translated into go back to origin-location, as shown in the position of detector in Fig. 1 (b), recycling is similarly swept
Condition is retouched, a pineapple is scanned, obtains the multipotency line integral value of pineapple, according to multipotency curve and line integral value, can be found pair
The length value answered completes multipotency further according to the available corresponding single energy line integrated value of single energy curve and the length value found
Line integral value then carries out the reconstruction of target cone beam computed tomography image to the correction of single energy line integrated value, obtains without hard
Change the target cone beam computed tomography image of artifact.
Curve matching of the invention is more accurate compared to conventional method, because can be in the effective condition of detector size
Under, larger lengths and corresponding line integral value are accurately obtained, ensure that the precision of curve matching.As shown in figure 5, Fig. 5 is tradition
The schematic diagram of multipotency curve and single energy curve under method, solid dot is the length value and line integral that acquisition is emulated under conventional method
The sampled point of value, solid-line curve are the multipotency curve being fitted under conventional method, and number line is that single energy after being fitted under conventional method is bent
Line emulates the length value and line integral of acquisition since the range of length value obtained under conventional direction is smaller under conventional method
The coordinate points quantity of value is few, thus it is worse for the precision for the multipotency curve matching being fitted under conventional method, in correction course
It is more inaccurate for the estimation of line integral value corresponding to larger lengths.It will be evident that the multipotency being fitted under conventional method in Fig. 5 is bent
Line is compared with the multipotency curve of the method for the present invention in Fig. 4, the multipotency curve " being raised " that is fitted under conventional method.And it is of the invention
The sampled point of method is more widened on Length Value Scope, and the multipotency curve of fitting and single energy curve are more accurate, improves hardening
Correction accuracy.
It should be understood that although each step in the flow chart of Fig. 2 to 3 is successively shown according to the instruction of arrow,
It is these steps is not that the inevitable sequence according to arrow instruction successively executes.Unless expressly stating otherwise herein, these steps
There is no stringent sequences to limit for rapid execution, these steps can execute in other order.Moreover, in Fig. 2 to 3 at least
A part of step may include that perhaps these sub-steps of multiple stages or stage are not necessarily in same a period of time to multiple sub-steps
Quarter executes completion, but can execute at different times, the execution in these sub-steps or stage be sequentially also not necessarily according to
Secondary progress, but in turn or can replace at least part of the sub-step or stage of other steps or other steps
Ground executes.
In one embodiment, as shown in fig. 6, Fig. 6 is cone beam computed tomography image rectification in one embodiment
The structural schematic diagram of system provides a kind of cone beam computed tomography image correction system in the present embodiment, and system includes
Background projection image acquisition module 310, correction model body projected image obtain module 320, single energy curve acquisition module 330 and to schools
Orthographic view correction module 340, in which:
Background projection image obtains module 310, for obtaining background projection image, wherein background projection image is the
Detector carries out the image that angularly circumference exposure scan is detected to gas medium under the conditions of one, and first condition is detector
Place plane is parallel to the angularly Pivot axle of circumference exposure scan, the central ray of radiographic source and passes perpendicularly through rotation center
The midpoint on the side boundary for being parallel to Pivot axle of axis and detector is irradiated by central ray.
Gas medium can be the required atmosphere under imaging circumstances, for example, it may be air, rare gas,
Nitrogen, a certain proportion of mixed gas, ionic steam, certain pressure intensity or temperature gas.Needs are such as imaged in vacuum environment, gas
The state of body medium also could alternatively be the state of no gas medium, to form vacuum environment.Angularly circumference exposure scan can
To detect the image under multiple angles.
Correction model body projected image obtains module 320, for obtaining correction model body projected image, wherein correction model body is thrown
Shadow image carries out the image that angularly circumference exposure scan is detected, correction to correction model body for detector in the first condition
Mold be placed on imaging visible area in and diameter of section be less than imaging visible area diameter die body, imaging visible area
For imageable areas of the field angle under first condition at Pivot axle.
Correction model body can make the cylindrical center's line and rotation centerline of correction model body in imaging visible area as far as possible
It substantially overlaps, detects available correction model body projected image by carrying out to correction model body.Correction model body can be it is cylindrical,
The shapes such as rectangle；The composition material of correction model body can be homogeneous substance, i.e. the density of correction model body is uniform, such as can
To be selected as equivalent water or pmma material etc..
Single energy curve acquisition module 330, it is bent for obtaining multipotency according to background projection image and correction model body projected image
Line, according to multipotency curve acquisition list energy curve, wherein multipotency curve is used to indicate the relationship of multipotency line integral value and length value,
Single energy curve is used to indicate the relationship of single energy line integrated value and length value.
It is single can curve acquisition module 330 according to background projection image and correction model body projected image can simulate radiographic source and
The scanning imagery process of detector simultaneously fits multipotency curve, further according to multipotency curve acquisition list energy curve.
Projection image correction module 340 to be corrected, for correcting perspective view to be corrected according to multipotency curve and single energy curve
Picture simultaneously generates target cone beam computed tomography image, wherein projected image to be corrected is detector pair under a second condition
Object under test carries out the image that angularly circumference exposure scan is detected, and plane where second condition is detector is parallel to rotation
Turn central axis, central ray passes perpendicularly through Pivot axle and central ray vertical irradiation is in the center of detector, object under test
To be placed on the object of Pivot axle and being in the environment of gas medium.
Projected image acquisition process to be corrected radiographic source central ray vertical irradiation at the center of detector, detection
Device can be imaged in the center of field angle.Projection image correction module 340 to be corrected can be bent according to the multipotency being fitted
The projected image to be corrected of line and single energy curve measuring targets is corrected, and obtains target cone beam computed tomography figure
Picture.
It is bent to obtain the higher multipotency of accuracy by second condition for above-mentioned cone beam computed tomography image correction system
Line and single energy curve, the projected image to be corrected of measuring targets are accurately corrected, and the accuracy of hardening correcting is improved.
Specific restriction about cone beam computed tomography image correction system may refer to above for cone-beam meter
The restriction of calculation machine tomographic imaging method for correcting image, details are not described herein.Above-mentioned cone beam computed tomography image rectification system
Modules in system can be realized fully or partially through software, hardware and combinations thereof.Above-mentioned each module can be in the form of hardware
It is embedded in or independently of the storage that in the processor in computer equipment, can also be stored in a software form in computer equipment
In device, the corresponding operation of the above modules is executed in order to which processor calls.
In one embodiment, a kind of computer equipment is provided, which can be server, internal junction
Composition can using as shown in fig. 7, Fig. 7 as the internal structure chart of computer equipment in one embodiment.The computer equipment includes logical
Cross processor, memory and the network interface of system bus connection.Wherein, the processor of the computer equipment is for providing calculating
And control ability.The memory of the computer equipment includes non-volatile memory medium, built-in storage.The non-volatile memories are situated between
Matter is stored with operating system, computer program and database.The built-in storage is the operating system in non-volatile memory medium
Operation with computer program provides environment.The network interface of the computer equipment is used to pass through network connection with external terminal
Communication.To realize a kind of cone beam computed tomography method for correcting image when the computer program is executed by processor.
It will be understood by those skilled in the art that structure shown in Fig. 7, only part relevant to application scheme is tied
The block diagram of structure does not constitute the restriction for the computer equipment being applied thereon to application scheme, specific computer equipment
It may include perhaps combining certain components or with different component layouts than more or fewer components as shown in the figure.
In one embodiment, a kind of computer equipment is provided, including memory, processor and storage are on a memory
And the computer program that can be run on a processor, processor perform the steps of when executing computer program
Obtain background projection image, wherein background projection image is that detector carries out gas medium in the first condition
The angularly image that circumference exposure scan is detected, plane where first condition is detector are parallel to angularly circumference exposure
What the Pivot axle of scanning, the central ray of radiographic source passed perpendicularly through Pivot axle and detector is parallel to Pivot axle
The midpoint on side boundary irradiated by central ray；
Obtain correction model body projected image, wherein correction model body projected image is detector in the first condition to correction
Die body carries out image that angularly circumference exposure scan is detected, and Correction Die is to be placed in imaging visible area and section
Diameter is less than the die body of the diameter of imaging visible area, and imaging visible area is field angle under first condition at Pivot axle
Imageable areas；
Multipotency curve is obtained according to background projection image and correction model body projected image, it can be bent according to multipotency curve acquisition list
Line, wherein multipotency curve is used to indicate the relationship of multipotency line integral value and length value, and single energy curve is for indicating that list can line integral
The relationship of value and length value；
According to multipotency curve and single energy curve, corrects projected image to be corrected and generate target cone beam computed tomography
Image, wherein projected image to be corrected is that detector measuring targets carry out angularly circumference exposure scan under a second condition
The image detected, second condition are that plane is parallel to Pivot axle, central ray passes perpendicularly through rotation at detector place
Central axis and central ray vertical irradiation is at the center of detector, object under test is to be placed on the object of Pivot axle and be in
In the environment of gas medium.
In one embodiment, it is also performed the steps of when processor executes computer program
According toObtain the diameter of imaging visible area, wherein D is the straight of imaging visible area
Diameter, L are the length of the detectable area of detector, and SAD is radiographic source at a distance from Pivot axle, and SDD is radiographic source and visits
Survey the vertical range of device.
In one embodiment, it is also performed the steps of when processor executes computer program
The background projection image of correction model body projected image and corresponding angle is subjected to logarithmic transformation, and obtains compensation line product
Partial image；Initial cone beam computed tomography image is established according to compensation line integral image, in initial cone-beam computer tomography
Image is partitioned into the region of correction model body, and generates and divide domain cone beam computed tomography image, wherein divides domain cone-beam meter
The pixel value in the region of correction model body is preset non-zero value in calculation machine tomographic imaging image, divides domain cone beam computed tomography figure
Pixel value as in other than the region of correction model body is zero；According to domain cone beam computed tomography image is divided, detector is obtained
The first corresponding length value of each detection and the corresponding line integral value of length value；According to length value and the corresponding line integral value of length value
It is fitted and obtains multipotency curve；According to multipotency curve acquisition list energy curve, wherein it is single can curve be that multipotency curve is in length value
Tangent line at zero.
In one embodiment, it is also performed the steps of when processor executes computer program
According toObtain compensation line integral image, wherein ln is pair that the truth of a matter is e
Number operation, integral are compensation line integral image, and P_cylinder is correction model body projected image, and P_air is corresponding angle
Background projection image, s is the serial number of angularly angle in circumference exposure scan, and integral (s) is the correction of s-th of angle
Line integral image, P_cylinder (s) are the correction model body projected image of s-th of angle, and P_air (s) is the back of s-th of angle
Scape projected image,For the background projection image of s-th angle and the respective pixel of correction model body projected image
Pixel value ratio.
In one embodiment, it is also performed the steps of when processor executes computer program
According in the length of the detectable area of detector, the width of the detectable area of detector, radiographic source and rotation
Distance, the vertical range of radiographic source and detector of mandrel, detection member of the calculating detector under default rotation angle are corresponding
Length value, wherein the corresponding length value of detection member is the ray of radiographic source when the ray of radiographic source reaches the detection member of detector
Penetrate the length of correction model body；The line for detecting first corresponding position is searched in the corresponding compensation line integral image of default rotation angle
Integrated value.
In one embodiment, it is also performed the steps of when processor executes computer program
Obtain projected image to be corrected；According to projected image to be corrected, multipotency curve and single energy curve, throwing to be corrected is corrected
Shadow image and the single energy line integrated value for obtaining projected image to be corrected；It is generated according to single energy line integrated value of projected image to be corrected
Target cone beam computed tomography image.
In one embodiment, it is also performed the steps of when processor executes computer program
The background projection image of projected image to be corrected and corresponding angle is subjected to logarithmic transformation, and obtains line product to be corrected
Partial image；The corresponding length value to be corrected of multipotency line integral value of line integral image to be corrected is searched in multipotency curve, wherein
The multipotency line integral value of projected image to be corrected is the pixel value of pixel in projected image to be corrected；By length value to be corrected in list
It can single energy line integrated value of the corresponding single energy line integrated value of curve as projected image to be corrected.
In one embodiment, a kind of computer readable storage medium is provided, computer program is stored thereon with, is calculated
Machine program performs the steps of when being executed by processor
Obtain background projection image, wherein background projection image is that detector carries out gas medium in the first condition
The angularly image that circumference exposure scan is detected, plane where first condition is detector are parallel to angularly circumference exposure
What the Pivot axle of scanning, the central ray of radiographic source passed perpendicularly through Pivot axle and detector is parallel to Pivot axle
The midpoint on side boundary irradiated by central ray；
Obtain correction model body projected image, wherein correction model body projected image is detector in the first condition to correction
Die body carries out image that angularly circumference exposure scan is detected, and Correction Die is to be placed in imaging visible area and section
Diameter is less than the die body of the diameter of imaging visible area, and imaging visible area is field angle under first condition at Pivot axle
Imageable areas；
Multipotency curve is obtained according to background projection image and correction model body projected image, it can be bent according to multipotency curve acquisition list
Line, wherein multipotency curve is used to indicate the relationship of multipotency line integral value and length value, and single energy curve is for indicating that list can line integral
The relationship of value and length value；
According to multipotency curve and single energy curve, corrects projected image to be corrected and generate target cone beam computed tomography
Image, wherein projected image to be corrected is that detector measuring targets carry out angularly circumference exposure scan under a second condition
The image detected, second condition are that plane is parallel to Pivot axle, central ray passes perpendicularly through rotation at detector place
Central axis and central ray vertical irradiation is at the center of detector, object under test is to be placed on the object of Pivot axle and be in
In the environment of gas medium.
In one embodiment, it is also performed the steps of when computer program is executed by processor
According toObtain the diameter of imaging visible area, wherein D is the straight of imaging visible area
Diameter, L are the length of the detectable area of detector, and SAD is radiographic source at a distance from Pivot axle, and SDD is radiographic source and visits
Survey the vertical range of device.
In one embodiment, it is also performed the steps of when computer program is executed by processor
The background projection image of correction model body projected image and corresponding angle is subjected to logarithmic transformation, and obtains compensation line product
Partial image；Initial cone beam computed tomography image is established according to compensation line integral image, in initial cone-beam computer tomography
Image is partitioned into the region of correction model body, and generates and divide domain cone beam computed tomography image, wherein divides domain cone-beam meter
The pixel value in the region of correction model body is preset non-zero value in calculation machine tomographic imaging image, divides domain cone beam computed tomography figure
Pixel value as in other than the region of correction model body is zero；According to domain cone beam computed tomography image is divided, detector is obtained
The first corresponding length value of each detection and the corresponding line integral value of length value；According to length value and the corresponding line integral value of length value
It is fitted and obtains multipotency curve；According to multipotency curve acquisition list energy curve, wherein it is single can curve be that multipotency curve is in length value
Tangent line at zero.
In one embodiment, it is also performed the steps of when computer program is executed by processor
According toObtain compensation line integral image, wherein ln is pair that the truth of a matter is e
Number operation, integral are compensation line integral image, and P_cylinder is correction model body projected image, and P_air is corresponding angle
Background projection image, s is the serial number of angularly angle in circumference exposure scan, and integral (s) is the correction of s-th of angle
Line integral image, P_cylinder (s) are the correction model body projected image of s-th of angle, and P_air (s) is the back of s-th of angle
Scape projected image,For the background projection image of s-th angle and the respective pixel of correction model body projected image
Pixel value ratio.
In one embodiment, it is also performed the steps of when computer program is executed by processor
According in the length of the detectable area of detector, the width of the detectable area of detector, radiographic source and rotation
Distance, the vertical range of radiographic source and detector of mandrel, detection member of the calculating detector under default rotation angle are corresponding
Length value, wherein the corresponding length value of detection member is the ray of radiographic source when the ray of radiographic source reaches the detection member of detector
Penetrate the length of correction model body；The line for detecting first corresponding position is searched in the corresponding compensation line integral image of default rotation angle
Integrated value.
In one embodiment, it is also performed the steps of when computer program is executed by processor
Obtain projected image to be corrected；According to projected image to be corrected, multipotency curve and single energy curve, throwing to be corrected is corrected
Shadow image and the single energy line integrated value for obtaining projected image to be corrected；It is generated according to single energy line integrated value of projected image to be corrected
Target cone beam computed tomography image.
In one embodiment, it is also performed the steps of when computer program is executed by processor
The background projection image of projected image to be corrected and corresponding angle is subjected to logarithmic transformation, and obtains line product to be corrected
Partial image；The corresponding length value to be corrected of multipotency line integral value of line integral image to be corrected is searched in multipotency curve, wherein
The multipotency line integral value of projected image to be corrected is the pixel value of pixel in projected image to be corrected；By length value to be corrected in list
It can single energy line integrated value of the corresponding single energy line integrated value of curve as projected image to be corrected.
Those of ordinary skill in the art will appreciate that realizing all or part of the process in above-described embodiment method, being can be with
Relevant hardware is instructed to complete by computer program, the computer program can be stored in a non-volatile computer
In read/write memory medium, the computer program is when being executed, it may include such as the process of the embodiment of above-mentioned each method.Wherein,
To any reference of memory, storage, database or other media used in each embodiment provided herein,
Including non-volatile and/or volatile memory.Nonvolatile memory may include read-only memory (ROM), programming ROM
(PROM), electrically programmable ROM (EPROM), electrically erasable ROM (EEPROM) or flash memory.Volatile memory may include
Random access memory (RAM) or external cache.By way of illustration and not limitation, RAM is available in many forms,
Such as static state RAM (SRAM), dynamic ram (DRAM), synchronous dram (SDRAM), double data rate sdram (DDRSDRAM), enhancing
Type SDRAM (ESDRAM), synchronization link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM
(RDRAM), direct memory bus dynamic ram (DRDRAM) and memory bus dynamic ram (RDRAM) etc..
Each technical characteristic of above embodiments can be combined arbitrarily, for simplicity of description, not to above-described embodiment
In each technical characteristic it is all possible combination be all described, as long as however, the combination of these technical characteristics be not present lance
Shield all should be considered as described in this specification.
The several embodiments of the application above described embodiment only expresses, the description thereof is more specific and detailed, but simultaneously
It cannot therefore be construed as limiting the scope of the patent.It should be pointed out that coming for those of ordinary skill in the art
It says, without departing from the concept of this application, various modifications and improvements can be made, these belong to the protection of the application
Range.Therefore, the scope of protection shall be subject to the appended claims for the application patent.
Claims (10)
1. a kind of cone beam computed tomography method for correcting image, which comprises the following steps:
Obtain background projection image, wherein the background projection image is that detector carries out gas medium in the first condition
The angularly image that circumference exposure scan is detected, plane where the first condition is detector are parallel to angularly circumference
The Pivot axle of exposure scan, the central ray of radiographic source pass perpendicularly through the parallel of the Pivot axle and the detector
It is irradiated in the midpoint on the side boundary of the Pivot axle by the central ray；
Obtain correction model body projected image, wherein the correction model body projected image is the detection under the first condition
Device carries out the image that angularly circumference exposure scan is detected to correction model body, and the correction model body is to be placed on imaging visually
In region and diameter of section is less than the die body of the diameter of the imaging visible area, and the imaging visible area is described first
Imageable areas of the field angle at the Pivot axle under part；
Multipotency curve is obtained according to the background projection image and the correction model body projected image, is obtained according to the multipotency curve
Take single energy curve, wherein the multipotency curve is used to indicate the relationship of multipotency line integral value and length value, and single energy curve is used
In the relationship for indicating single energy line integrated value and length value；
According to the multipotency curve and single energy curve, corrects projected image to be corrected and generate target cone-beam computer tomography
Image, wherein the projected image to be corrected is that the detector measuring targets carry out angularly under a second condition
The image that circumference exposure scan is detected, plane where the second condition is the detector are parallel to the rotation center
Axis, the central ray pass perpendicularly through the Pivot axle and the central ray vertical irradiation in the detector
The heart, the object under test are to be placed in the object of the Pivot axle and the environment in the gas medium；
The diameter of the imaging visible area is obtained by following manner:
According toThe diameter of the imaging visible area is obtained,
Wherein, D is the diameter of the imaging visible area, and L is the length of the detectable area of the detector, and SAD is described
For radiographic source at a distance from the Pivot axle, SDD is the vertical range of the radiographic source and the detector.
2. cone beam computed tomography method for correcting image according to claim 1, which is characterized in that described according to institute
It states background projection image and the correction model body projected image obtains multipotency curve, according to the multipotency curve acquisition list energy curve
The step of, comprising the following steps:
The background projection image of the correction model body projected image and corresponding angle is subjected to logarithmic transformation, and obtains compensation line product
Partial image；
Initial cone beam computed tomography image is established according to the compensation line integral image, in the initial cone-beam computer
Tomographic imaging image segmentation goes out the region of the correction model body, and generates and divide domain cone beam computed tomography image, wherein institute
The pixel value for stating the region of correction model body in point domain cone beam computed tomography image is preset non-zero value, described to divide domain cone-beam
Pixel value other than the region of correction model body described in computer tomography image is zero；
Divide domain cone beam computed tomography image according to described, obtain the corresponding length value of the detector each detection member and
The corresponding line integral value of the length value；
It is fitted according to the length value and the corresponding line integral value of the length value and obtains the multipotency curve；
Single energy curve according to the multipotency curve acquisition, wherein single energy curve is the multipotency curve in the length
Angle value is the tangent line at zero.
3. cone beam computed tomography method for correcting image according to claim 2, which is characterized in that it is described will be described
The background projection image of correction model body projected image and corresponding angle carries out logarithmic transformation, and obtains the step of compensation line integral image
Suddenly, comprising the following steps:
According toObtain the compensation line integral image, wherein ln is pair that the truth of a matter is e
Number operation, integral are the compensation line integral image, and P_cylinder is the correction model body projected image, and P_air is
The background projection image of the corresponding angle, s are the serial number of angle in angularly circumference exposure scan, and integral (s) is s
The compensation line integral image of a angle, P_cylinder (s) are the correction model body projected image of s-th of angle, and P_air (s) is
The background projection image of s-th of angle,For background projection image and the correction model body projection of s-th angle
The ratio of the pixel value of the respective pixel of image.
4. cone beam computed tomography method for correcting image according to claim 2, which is characterized in that described according to institute
A point domain cone beam computed tomography image is stated, the first corresponding length value of each detection of the detector and the length value are obtained
The step of corresponding line integral value, comprising the following steps:
According to the length of the detectable area of the detector, the width of the detectable area of the detector, the radiographic source
With at a distance from the Pivot axle, the vertical range of the radiographic source and the detector, calculate the detector default
Rotate the corresponding length value of detection member under angle, wherein the first corresponding length value of detection is the ray of the radiographic source
The ray of the radiographic source penetrates the length of the correction model body when reaching the detection member of the detector；
The line integral value for detecting first corresponding position is searched in the corresponding compensation line integral image of angle in default rotate.
5. cone beam computed tomography method for correcting image according to claim 1, which is characterized in that described according to institute
Multipotency curve and single energy curve are stated, projected image to be corrected is corrected and generates target cone beam computed tomography image
Step, comprising the following steps:
Obtain the projected image to be corrected；
According to projected image, the multipotency curve and single energy curve to be corrected, the projected image to be corrected is corrected
And obtain single energy line integrated value of the projected image to be corrected；
The target cone beam computed tomography image is generated according to single energy line integrated value of the projected image to be corrected.
6. cone beam computed tomography method for correcting image according to claim 5, which is characterized in that described according to institute
Projected image, the multipotency curve and single energy curve to be corrected are stated, is corrected described in the projected image to be corrected and acquisition
The step of single energy line integrated value of projected image to be corrected, comprising the following steps:
The background projection image of the projected image to be corrected and corresponding angle is subjected to logarithmic transformation, and obtains line product to be corrected
Partial image；
The corresponding length value to be corrected of multipotency line integral value of the line integral image to be corrected is searched in the multipotency curve,
Wherein, the multipotency line integral value of the projected image to be corrected is the pixel value of pixel in the projected image to be corrected；
Using the length value to be corrected in the corresponding single energy line integrated value of the list energy curve as the projected image to be corrected
Single energy line integrated value.
7. cone beam computed tomography method for correcting image according to any one of claim 1 to 6, feature exist
In the array size of the detection member of, the detector be M × N, the background projection image, the correction model body projected image and
The matrix size of projected image to be corrected is M × N, wherein M and N is positive integer.
8. a kind of cone beam computed tomography image correction system, which is characterized in that the system comprises:
Background projection image obtains module, for obtaining background projection image, wherein the background projection image is at first
Detector carries out the image that angularly circumference exposure scan is detected to gas medium under part, and the first condition is detector
Place plane is parallel to the angularly Pivot axle of circumference exposure scan, the central ray of radiographic source and passes perpendicularly through the rotation
The midpoint on the side boundary for being parallel to the Pivot axle of central axis and the detector is irradiated by the central ray；
Correction model body projected image obtains module, for obtaining correction model body projected image, wherein the correction model body perspective view
As carrying out the image that angularly circumference exposure scan is detected to correction model body for the detector described under the first condition,
The correction model body be placed on imaging visible area in and diameter of section be less than it is described be imaged visible area diameter die body,
The imaging visible area is imageable areas of the field angle at the Pivot axle under the first condition；
Single energy curve acquisition module, it is bent for obtaining multipotency according to the background projection image and the correction model body projected image
Line, according to the multipotency curve acquisition list energy curve, wherein the multipotency curve is for indicating multipotency line integral value and length value
Relationship, it is described it is single can curve be used to indicate the relationship of single energy line integrated value and length value；
Projection image correction module to be corrected, for correcting projection to be corrected according to the multipotency curve and single energy curve
Image simultaneously generates target cone beam computed tomography image, wherein the projected image to be corrected is institute under a second condition
It states detector measuring targets and carries out the image that angularly circumference exposure scan is detected, the second condition is the detection
Plane is parallel to the Pivot axle, the central ray passes perpendicularly through the Pivot axle and the center is penetrated where device
For line vertical irradiation at the center of the detector, the object under test is to be placed on the object of the Pivot axle and in institute
It states in the environment of gas medium；
The diameter of the imaging visible area is obtained by following manner:
According toThe diameter of the imaging visible area is obtained,
Wherein, D is the diameter of the imaging visible area, and L is the length of the detectable area of the detector, and SAD is described
For radiographic source at a distance from the Pivot axle, SDD is the vertical range of the radiographic source and the detector.
9. a kind of computer equipment including memory, processor and stores the meter that can be run on a memory and on a processor
Calculation machine program, which is characterized in that the processor realizes any one of claims 1 to 7 institute when executing the computer program
The step of cone beam computed tomography method for correcting image stated.
10. a kind of computer readable storage medium, is stored thereon with computer program, which is characterized in that the computer program
Cone beam computed tomography method for correcting image described in any one of claims 1 to 7 is realized when being executed by processor
Step.
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